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[94.113.223.73]) by smtp.gmail.com with ESMTPSA id v184sm20963871wma.6.2019.03.27.02.57.50 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 27 Mar 2019 02:57:50 -0700 (PDT) Date: Wed, 27 Mar 2019 10:57:49 +0100 From: Jiri Pirko To: Michal Kubecek Cc: David Miller , netdev@vger.kernel.org, Jakub Kicinski , Andrew Lunn , Florian Fainelli , John Linville , Stephen Hemminger , linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next v5 07/22] ethtool: netlink bitset handling Message-ID: <20190327095749.GD6979@nanopsycho> References: <9123f942b484ef4bbb684bb1f4aa2b70d673a259.1553532199.git.mkubecek@suse.cz> <20190326155911.GA4958@nanopsycho.orion> <20190326175932.GN26076@unicorn.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190326175932.GN26076@unicorn.suse.cz> User-Agent: Mutt/1.11.3 (2019-02-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Tue, Mar 26, 2019 at 06:59:32PM CET, mkubecek@suse.cz wrote: >On Tue, Mar 26, 2019 at 04:59:11PM +0100, Jiri Pirko wrote: >> Mon, Mar 25, 2019 at 06:08:15PM CET, mkubecek@suse.cz wrote: >> >Declare attribute type constants and add helper functions to generate and >> >parse arbitrary length bit sets. >> >> Hmm, this looks like a lot of work. Two things: >> 1) This is generic. Not really related to ethtool in any way. Could this >> be done in netlink common code? > >I suppose it could if other netlink based APIs would be interested in >using it. The only ethtool specific part is the support for "legacy >style names" (fixed size strings) but that is something I'm not really >happy about. Perhaps it's time to return to the original idea of >supporting only arrays of (char *) and creating them around existing >fixed size ones. Wait, could you please describe this more? > >> 2) Did you think about leveraging NLA_BITFIELD32? What I mean is this: >> NEST_START >> NLA_BITFIELD32 index 0 (bit 0-31) >> NLA_BITFIELD32 index 1 (bit 32-63) >> NLA_BITFIELD32 index 2 (bit 64-95) >> NLA_BITFIELD32 index 3 (bit 96-127) >> .... >> NEST_END >> It is basically an array of NLA_BITFIELD32. > >That would be similar to compact form but it would introduce the >interleaving and extra struct nlattr header for each block. I don't >think it would make things easier. I'm just trying to figure out if it would be possible to use existing building block instead of introducing new ones.... > >The verbose form is meant to allow requests like > > ethtool -K eth0 tx-vlan-stag-hw-insert on > ethtool -s eth0 advertise 1000baseT/Full off > >without either keeping the table of available flags in sync between >kernel and userspace (all userspace users of the API) or having to ask >for the list first (in case of one shot requests as above; long running >tools like "ethtool --monitor" or config management daemons would keep >the tables and use compact form). Okay, I have to go over those patches but this smells. > >Michal